Japanese Patent Application Laid-Open No. 2014-96976, Japanese Patent Application Laid-Open No. 2011-193678, and Japanese Patent Application Laid-Open No. 2014-82926 disclose direct power converters. The direct power converters disclosed by these include a booster circuit and a capacitor that maintains a voltage boosted by the booster circuit. In the DC power to be supplied to an inverter, the power from the capacitor and the power obtained from a diode rectifier are appropriately processed. Consequently, the inverter receives increased DC voltage.
Although Japanese Patent No. 4067021 also discloses a direct power converter, the direct power converter includes neither the booster circuit nor the capacitor. On the other hand, the direct power converter includes, at an input side of the inverter, an LC filter that suppresses a carrier current of the inverter.
The direct power converter disclosed by Japanese Patent Application Laid-Open No. 2014-96976 includes not only the booster circuit and the capacitor but also the LC filter. Furthermore, the direct power converter includes a diode between the capacitor and the LC filter to prevent a current from flowing from the capacitor to the LC filter.
In any of Japanese Patent Application Laid-Open No. 2014-96976, Japanese Patent No. 4067021, and Japanese Patent No. 5257533, a current for suppressing resonance of the LC filter (hereinafter referred to as a “suppressing current”) is obtained from a voltage generated in a reactor of the LC filter (or a voltage generated in a capacitor of the LC filter), and is superimposed on a current flowing through the inverter (hereinafter referred to as an “inverter current”).